Weldability of dissimilar joint between F82H and SUS316L under fiber laser welding

•The microstructure of F82H/SUS316L dissimilar joint can be divided into four regions.•In the case without beam position shift, hardness of WM cannot be reduced by PWHT.•The fiber laser welding would be applicable for constructing the dissimilar joint. As one of the high beam quality heat sources, 4kW fiber laser was applied for joining between reduced activation ferritic/martensitic steel, F82H and SUS316L austenitic stainless steel, and the microstructural analyses and Vickers hardness measurements were carried out before and after post-weld heat treatment (PWHT). The microstructure of joint can be divided into four regions which are base metal of F82H, heat affected zone (HAZ) in F82H, weld metal (WM) and base metal of SUS316L. Also, it is revealed that the high-power fiber laser can be employed for constructing butt joint between F82H and SUS316L by applying PWHT and shifting the laser beam position to SUS316L, where the distance between the contact face and beam should be set as a range from radius to diameter of laser beam.